Currently, a lithium ion secondary battery mainly is used as a power source of mobile equipment such as a mobile telephone and a notebook computer. However, the further increase in the capacity of the lithium ion secondary battery is reaching a limit, and a small fuel cell is drawing attention as an energy device capable of realizing the further increase in capacity.
As the small fuel cell, various types of systems have been designed. Among them, a direct methanol type fuel cell (DMFC) is considered to be most practical. The DMFC is a fuel cell capable of supplying methanol as a fuel directly to an electrode, and obtaining electricity when water and carbon dioxide are generated from methanol and oxygen. Due to the direct supply of methanol as a fuel, a fuel reformer and other auxiliary appliances can be substantially omitted, so that a very high energy density is expected.
However, regarding the mobile equipment, an equipment body or a fuel storage container may be damaged due to dropping or the like. Particularly, in the case of dropping the fuel storage container, there is a possibility that a fuel may leak out due to the damage of a fuel supply port.
Furthermore, there is a possibility that the following accidents may occur: a user removes a contained fuel through the fuel supply port mischievously or intentionally, drinks the fuel by mistake, inhales a great amount of vapor thereof, and the like. Particularly, in the case where a fuel is harmful to a human body or is inflammable, some system for preventing the above-mentioned situations is required in the fuel storage container.
FIG. 12 shows an exemplary configuration of a conventional fuel cartridge for a fuel cell. A fuel cartridge 1 includes a fuel storage container 2 for storing a fuel, a fuel supply port 4 for supplying the fuel to equipment, and a fuel supply valve (check valve) 3 provided at the fuel supply port 4 so as to enable the fuel to be supplied only when the fuel is supposed to be supplied (e.g., see JP 2002-270210 A).
Furthermore, a fuel cartridge for a fuel cell has been proposed, which has a fuel storage container, a fuel supply port for supplying a fuel, a fuel supply valve enabling a fuel to be supplied, and a back pressure regulator for setting the internal pressure of the fuel storage container to be lower than an external pressure when the fuel is not supplied (see JP 2003-217618 A). The back pressure regulator sets the pressure in the fuel storage container to be always lower than the pressure outside the fuel cartridge, thereby preventing the internal pressure from increasing due to the vaporization of a liquid fuel in the fuel storage container to cause the leakage of the fuel.
As a method for supplying a fuel in a fuel cartridge to a fuel cell, a method for supplying a fuel by allowing a hollow needle provided at the fuel cell to pass through a partition wall provided at a fuel supply port of the fuel cartridge has been proposed (e.g., see U.S. Patent Application Publication No. 2003/0207158 A1, U.S. Pat. No. 6,460,733 B2).